Web guiding roller

ABSTRACT

A web guiding system for a web-fed rotary printing press includes a web guide roller which contacts the printed surface of a print-carrying web. The effective diameter of the transfer cylinder which prints the print-carrying web is the same as, or is an integral multiple of the diameter of the web guide roller.

FIELD OF THE INVENTION

The present invention relates to a web guide roller for a web-fed rotaryprinting press. The print carrying web is guided over a driveable webguide roller with its printed side in contact with the web guide roller.The printed surface of the web is not smudged.

DESCRIPTION OF THE PRIOR ART

A web-fed rotary printing press is known from DE 29 51 246 C2. Thisprior device has at least one paper guide roller for reversing the paperweb downstream of the last print unit in the running direction.

When the printed side of the paper web comes into contact with the paperguide roller, ink deposits occur on the paper guide roller, which canresult in smudging of the printed image.

JP-A-57-193368 describes guide rollers whose diameter is equal to thediameter of a rubber blanket cylinder of a print unit.

SUMMARY OF THE INVENTION

The object of the present invention is based on providing a web guideroller.

In accordance with the present invention, the object is attained by theprovision of at least one driveable web guide roller whose surfacecontacts the printed side of the print carrying web. The size of the webguide roller, and its rotational speed are selected so that there is nosmudging of the print image on the print carrying web as it comes incontact with the web guiding roller.

The advantages which can be achieved by the present invention consist,in particular, in that the printed print-carrying web does not cause anydeposit of printing ink on the web guide roller and therefore nosmudging of the print image occurs when the printed web comes intocontact with the web guide roller. This is achieved, on the one hand, byan oleophobic surface, for example made of chromium of the web guideroller, and on the other hand in that the web guide roller has anoleophilic surface such as a rubber packing or rubber cover. Thus,possible ink deposits on the surface of the web guide roller now occurharmlessly always at the same location.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will be explained in greater detail in whatfollows by means of a preferred embodiment. The sole drawing FIGUREshows the schematic representation of print units of a web-fed rotaryprinting press with a web guide roller in accordance with the presentinvention.

At least two known print units 1, 2, with four printing groups 16, 17,18, 19 of, for example, a so-called tower of eight, are arranged on topof each other in a web-fed rotary printing press. Each printing group 16to 19 has respectively, one transfer cylinder, for example a rubberblanket cylinder 3 or 4, and respectively, one printing cylinder, forexample plate cylinders 6 or 7. The cylinders 3, 4, 6, 7 of eachprinting group 16 to 19 are connected with each other by means of knowntoothed gears, for example.

Printing in one color each can be performed with each respectiveprinting group 16 to 19, which individual colors are supplied to theplate cylinders 6 or 7 by respective ink ducts, not specificallyrepresented. Moreover, it is also possible to assign damping units, notspecifically represented, to each plate cylinder 6 or 7 of the printinggroups 16 to 19. Each of the rubber blanket cylinders 3, 4 can be placedagainst the other, or respectively against a passing print-carrying web,for example a paper web 8.

After leaving the print units 1, 2, the paper web 8 is guided in therunning direction F over a web guide roller, such as, for example, apaper guide roller 9, and is reversed in the process. In this case, thepaper web 8 rests against or contacts the surface of the paper guideroller 9 over an angle of, for example, 90 or less/greater. The paperguide roller 9 has an exterior radius d, which corresponds to and is thesame as the effective exterior radius e of a rubber blanket cylinder 3or 4.

The radius e of the transfer cylinder 3 or 4 corresponds to an effectiveconveying radius e, on whose basis the conveying speed of the paper web8 can be fixed as a function of the number of revolutions of thetransfer cylinder.

In printing operations, this radius e is less than a radius of therubber blanket cylinder in a free state of the rubber blanket cylinder.In a technical sense, the effective radius e of the rubber blanketcylinder, in printing operations, is equal to the radius e of the webguide roller, i.e. tolerances are permissible as long as no slippageoccurs on the rubber blanket cylinder and on the web guide roller. Suchtolerances only result in negligible changes of the web tension.

The paper guide roller 9 has either an oleophilic surface 11, i.e. it isprovided with a rubber blanket, for example, or has an oleophobicsurface 11, for example a chromium cover.

In accordance with a first preferred embodiment, the print units 1, 2,as well as the paper guide roller 9, are each connected with separateangle of rotation-position controlled drive mechanisms, for examplemotors 12, 13, 14. An angle of rotation sensor, 27, 28, 29 is assignedto each motor 12 to 14. Each motor 12 to 14 and each position sensor isconnected with a drive regulator, 30, 31, 32. All drive regulators 30,31, 32 are connected with each other via a data bus 33. By means of thisarrangement of angle of rotation sensors 27, 28, 29; drive regulators30, 31, 32; and data bus 33, an angular synchronicity is providedbetween the rubber blanket cylinder 3 or 4 of the print unit 1, as wellas between the rubber blanket cylinder 3 or 4 of the print unit 2, andthe paper guide roller 9, in that all can be driven at the sameconveying speed.

In accordance with a second preferred embodiment, each one of the printunits 1 and 2 is connected via a coupling, via a bevel gear, via asynchronizing or vertical shaft, via a vertical shaft coupling and via abevel gear with a synchronizing or longitudinal shaft all of which arenot specifically represented. The couplings can be known,register-maintaining couplings and can each consist of an upper and of alower coupling plate. The rubber blanket cylinder 3 or 4 of eachprinting group 16 to 19 is provided with an absolute value sensor,which, by known electronic means, signals only one possible angularposition of the driven rubber blanket cylinder 4 for the synchronouscoupling-in of the printing group. The absolute value sensor consists ofa circular disk with angular division. In place of the absolute valuesensor, it is also possible to use a known so-called one-value coupling,which also permits the coupling process in only one possible angularposition.

In connection with an advantageous preferred embodiment, thecircumference of the paper guide roller 9 can be adaptable to theeffective circumference of the rubber-elastic packing of the rubberblanket cylinder 3 or 4 in order to compensate for possible tolerances.For this purpose, the paper guide roller 9 may have a circumferentiallyadjustable rubber- or plastic coated surface 11, which is notspecifically shown.

The circumferential adjustability is achieved, for example, by the useof a circumferentially variable cylinder-like support element, which hasa number of shell segments. These shell segments are embodied in awedge-like manner on their inside and cooperate with counter wedgesarranged in the axial direction of the guide roller 9. A cylindricalhelical spring has been threaded on this support element. One end ofthis spring is connected with the guide roller shaft, and the other endof this spring is connected with a tensioning device in order to changethe circumference of the helical spring.

In accordance with a further preferred embodiment, an oleophilic paperguide roller 9 can also have an endless rubber coating, a so-calledsleeve.

In the same way, it is possible to produce an oleophilic paper guideroller 9 in which a cylinder base body is surrounded by a shell-likesupport plate carrying a rubber blanket. The angled legs of the supportplate are held in a secant-like slit of the cylinder base body.

In accordance with another preferred embodiment, the oleophobic surfaceof a paper guide roller 9 which is, for example, coated with chromium,can be made with an adjustable circumference in that initially the shaftjournals are provided with rotatable inlets. In this way, a heatableliquid, for example water or oil, can be passed through the rollerinterior.

By appropriate heating of the liquid, and the different heat expansionconnected with this, it is possible to change the radius d, or thecircumference of the paper guide roller 9 by a few millimeters. Possibletolerance variations between the circumferences of the rubber blanketcylinders 3 or 4 and the paper guide roller 9 can be compensated bymeans of this heating of the guide roller 9.

It is finally also possible, in accordance with the present invention,that the radius d of the driveable paper guide roller 9 is selected tocorrespond to a whole number fraction 1/n (for example wherein n=2) of aradius e, for example ha ½ portion, of a rubber blanket cylinder 3 or 4of a printing group 16 to 19. In this case, a plate cylinder 6 or 7 ofthe printing group 16 to 19 has approximately the radius d of the paperguide roller 9. This is also possible with double circumference pressesand double productions, i.e. with two identical subjects on thecircumference of the printing cylinder, or respectively plate cylinder 6or 7.

The circumferential speed of the rubber blanket cylinders 3 or 4 and ofthe driven paper guide cylinder 9 can be equal. A possible deposit ofink from the printed surface of the web 8 to the surface 11 of the guideroller 9 always takes place at the same location on the surface 11, orrespectively on the circumference of the paper guide roller 9, andtherefore will have only a harmless effect.

Alternatively, the radius d of the driveable paper guide roller 9 cancorrespond to a whole number multiple, for example twice that of aneffective radius e of a rubber blanket cylinder 3 or 4 of a printinggroup 16 to 19, wherein the circumferential speed is respectively thesame.

The driveable paper guide roller, or respectively web guide roller 9,can also act as a traction roller 21. In a special case, it is possibleto assign a counter roller 22 which, when required, can be driven by amotor 23, to the traction roller 21 driven by the motor 14. The counterroller 22 can also be seated in support arms, not specificallyrepresented, and can be designed so, that it can be placed against thetraction roller 21 by use of a spring force. The motor 23 can also beflanged to the counter roller 22, and the motor 14 can also be flangedto the paper guide roller 9.

Finally, it is also possible to use the driveable paper guide roller, orrespectively web guide roller 9, together with the driveable counterroller 22 as a web catching device 24.

If, for example, the paper web 8 tears at an imagined tear spot 26located downstream of the web catching device 24, the web guide roller 9can roll up the paper web 8, which is now pushed up in the runningdirection F, until the web-fed rotary printing press has come to a stop.

While preferred embodiments of a web guiding roller in accordance withthe present invention have been set forth fully and completelyhereinabove, it will be apparent to one of skill in the art that anumber of changes in, for example, the type of printing cylinders used,the style of printing being done, and the like could be made withoutdeparting from the true spirit and scope of the present invention whichis accordingly to be limited only by the following claims.

What is claimed is:
 1. A web-fed rotary printing press comprising: atleast one printing group for printing a printed image on aprint-carrying web passing through said at least one printing group; atleast one transfer roller in said at least one printing group, saidtransfer roller having a transfer cylinder surface and a transfercylinder free radius, said transfer cylinder further having a transfercylinder effective radius defined as a radius of said at least onetransfer cylinder during printing of the printed image on the printcarrying web as the print carrying web passes through said at least oneprinting group, said effective radius being less than said free radius;at least one driveable web guide roller located after, in a web runningdirection said at least one printing group to receive the print carryingweb with the printed image from said at least one printing group, saidat least one web guide roller having a web guide surface touching aprinted side of the print-carrying web and having a web guide rollerradius which, during operation of said at least printing group, is equalto said transfer cylinder effective radius; and means for driving saidweb guide roller and said transfer cylinder in angular synchronicity,the printed image printed on the printed side of the print carrying webby said at least one printing group always contacting the same locationon said web guide surface of said at least one web guide roller.
 2. Theweb-fed rotary printing press of claim 1 wherein said web guide rollersurface is oleophobic.
 3. The web-fed rotary printing press of claim 1wherein said web guide roller has a rubber-coated surface.
 4. A web-fedrotary printing press comprising: at least one printing group forprinting a printed image on a print-carrying web passing through said atleast one printing group; at least one printing cylinder in saidprinting group, said at least one printing cylinder having a printingcylinder diameter; at least one transfer cylinder in said at least oneprinting group, said at least one transfer cylinder having a transfercylinder surface and a transfer cylinder free radius, said transfercylinder further having a transfer cylinder effective radius defined asa radius of said at least one transfer cylinder during printing of theprinted image on the print carrying web as the print carrying web passesthrough said at least one printing group, said effective radius beingless than said free radius; at least one driveable web guide rollerlocated after, in a web running direction said at least one printinggroup to receive the print carrying web with the printed image from saidat least one printing group, said at least one web guide roller having aweb guide surface touching a printed side of the print-carrying web andhaving a web guide roller radius and diameter, said web guide rollerradius, during operation of said at least one printing group, beingequal to a whole number fraction (1/n) of said transfer cylindereffective radius, said web guide roller diameter being approximatelysaid printing cylinder diameter; and means for driving said web guideroller and said transfer cylinder in angular synchronicity, the printedimage printed on the printed side of the print carrying web by said atleast one printing group always contacting the same location on said webguide surface of said at least one web guide roller.
 5. The web-fedrotary printing press of claim 4 wherein said web guide roller surfaceis oleophobic.
 6. The web-fed rotary printing press of claim 4 whereinsaid web guide roller has a rubber-coated surface.
 7. A web-fed rotaryprinting press comprising: at least one printing group for printing aprinted image on a print-carrying web passing through said at least oneprinting group; at least one transfer cylinder in said at least oneprinting group, said at least one transfer cylinder having a transfercylinder surface and a transfer cylinder free radius, said transfercylinder further having a transfer cylinder effective radius defined asa radius of said at least one transfer cylinder during printing of theprinted image on the print carrying web as the print carrying web passesthrough said at least one printing group, said effective radius beingless than said free radius; at least one driveable web guide rollerlocated after, in a web running direction said at least one printinggroup to receive the print carrying web with the printed image from saidat least one printing group, said at least one web guide roller having aweb guide surface touching a printed side of the print-carrying web andhaving a web guide roller radius, wherein during printing operation ofsaid at least one printing group, said web guide roller radius is equalto a whole number multiple of said transfer cylinder effective radiusoperating under a load of said at least one printing group; and meansfor driving said web guide roller and said transfer cylinder in angularsynchronicity, the printed image printed on the printed side of theprint carrying web by said at least one printing group always contactingthe same location on said web guide surface of said at least one webguide roller.
 8. The web-fed rotary printing press of claim 7 whereinsaid web guide roller surface is oleophobic.
 9. The web-fed rotaryprinting press of claim 7 wherein said web guide roller rubber-coatedsurface.